On Wednesday, PNB, in a regulatory filing to BSE Ltd, said it had detected fraudulent transactions worth $1,771.7 million (over Rs11, 000 crore) in its Mumbai branch.

The Central Bureau of Investigation (CBI) is investigating billionaire jewellery designer Nirav Modi and a jewellery company after receiving two complaints from Punjab National Bank (PNB) which detected a Rs 11,000-crore fraud case.

On Wednesday, PNB, in a regulatory filing to BSE Ltd, said it had detected fraudulent transactions worth $1,771.7 million (over Rs11, 000 crore) in its Mumbai branch.

CBI received the complaints about the transactions detected by the public sector bank late last night, sources said.

The allegations are being looked into and future course of action will be decided soon, they said.

The agency has refused to share any further details as it may hamper the investigation. Agency sources said Modi is already facing a CBI probe on a complaint from the Punjab National Bank.

On February 5, CBI had booked Modi, along with his wife Ami Modi, brother Nishal Modi and his maternal uncle Mehul Choksi in connection with an alleged Rs 280-crore fraud case after it received a complaint from PNB on January 29.

In a statement, PNB said that the transactions in question are contingent in nature and liability arising out of these on the bank shall be decided based on the law and genuineness of underlying transactions.

After the disclosure on Wednesday, the bank's share price slipped as much as 5.9 per cent in early trade ad continued the downward trend later in the day. At 13:45 hours IST, the stock price Punjab National Bank was quoting at Rs 150.15, down Rs 11.50, or 7.11 per cent on the BSE.